A general mechanism for oxidative phosphorylation

Vol. 4, No. 2,196l

BIOCHEMICAL

AND BIOPHYSICAL RESEARCH COMMUNICATIONS

A GENRRAL MEClL4NISM FOR ORIDATIVE

PHOSPIiORYLATTON=

R. Duncan Dallas? Department of Biochemistry of Louisville School of Medicine Louisville, Kentucky

University

Received

January

We have isoprenoid

3, 1961

recently side

presented

chain

of vitamin

phosphorylation

in ultraviolet

Taylor,

At that

1959).

quinones fully ration

at the @,r

mechanisms

for

or corresponding mechanisms prior

to or accompanying

1954,

Clark

posed

chemical

et.

formation suitable

1 2

mechanisms associated

involved acceptor

A newly below.

1958,

al.,

of the

oxidation

with

oxidation

side

of quinol

chain

with

into

these

phosphate

quinones These

and other 1960)

participating

the reaction

are

unsatu-

to form a chroman

In these

phosphates

of a quinol

all

chemical

1958 and Chmielewska,

oxidation,

i.e.,

alternative

reduction.

Harrison,

of the

the above requisites. side

&

similarity

chain

phosphate

oxidative (Dallam

E groups,

presented

of the

to restore

mitochondria

an isoprenoid

of inorganic

cyclization

it

and vitamin

t possessing

tocopherols

for

out the chemical

We also

introduction

required

phorylation

possess

the cyclization

liver

we pointed

position.

the

in order

K,

K, ubiquinone

and all

requiring

irradiated

time

of the vitamin substituted

evidence

preceeding

either (Wessels,

pro-

in phosATP

in the presence

of a

such as ADP.

proposed

The necessity

mechanism for

revision

for

oxidative

phosphorylation

of our original

proposal,

is presented and those

of

Supported by grants from the American Heart Association, The National Science Foundation (G-1157), and the United States Public Health Service (ii-2102C) A portion of this work was done during the tenure of an Established Investigator-ship of the American Heart Association 106

Vol. 4, No. 2,196l

others,

BIOCHEMICAL

is

due to an apparent

and the existing equally 1954)

well would

require

that

almost

demand that for

mechanisms

exchange. are incorrect.

more accurately

depict

phosphorylation

when and if

it

would

appear

mechanisms

quinones

occurs

ubiquinone reduction

member to yield

I

configuration

presumably

inorganic

phosphate

to ADP under We are aid

proper

of oxidized

3II 0

paraquinone

E vitamins.

IV which

conditions

compounds

Compound III

possessing

groups,

i.e.,

Compound II chain

is held

in its

can then

yielding

the validity and are,

for

hypothesis.

107

donate

an iso-

vitamin

from

oxidized

electrophilic of nucleophilic

the energized

phosphate

ATP and the starting

quinone.

of the above proposal

through

the present,

K,

results

and is

by the enzyme and in the presence

yields

investigating

of synthetic

as a working

substituted

to one of the quinoid

III.

may

’ ’

by one of the members of the respiratory

by another

previously

oxidative

i’

-aI

II

and the group

the

0 0

ADP

adjacent

al.,

does not

of mitochondrial

ATP

chain

-et.

are involved.

-on

side

and

presented,therefore,

A

prenoid

X-P,

that

I

Compound I can be any fully

rapidly (Boyer,

compound,

The mechanism

the chemical

proposals

of substrate

intermediate

Thus,

the various

exchange

or absence

the

RESEARCH COMMUNICATIONS

between

Pi-ATP

in the presence

oxidation

proposed

discrepancy

The fact

data.

either

AND BIOPHYSICAL

accepting

this

the scheme

Vol. 4, No. 2,196l

BIOCHEMICAL

AND BIOPHYSICAL

RESEARCH COMMUNICATIONS

REFERENCES

Boyer, P. D., A. B. Falcone and Chmielewska, I., Biochim Biophye. Clark, W. M., G. W. Kirby and A. Dallam, R. D., and J. F. Taylor, Harrison, W., Nature, 181, 1131 Wessels, V. C., Rec. trav. chim.,

W. Il. Harrison, Nature=, 401 (1954) Acta., 39, 170 (1960) Todd, Nature, 181, 1650 (1958) Fed. Proc., l8, 826 (1959) (1958) 73, 529 (1954)

108